H reflex

Definition: a monosynaptic reflex consistently obtained in normal adults only by electrically stimulating the tibial nerve, generally in the popliteal fossa, while recording from the gastrocnemius-soleus muscle group; similar to the clinically elicited Achilles reflex, except that the neuromuscular spindles are bypassed. Widely used in the EMG laboratory to diagnose S1 radiculopathies and polyneuropathies.